Js: get the maximum zindex (Z-index) value of the page

js: Get the largest zIndex(z-index) value

//  You need to execute after the page is rendered 

function getMaxZIndex(){
    
 let arr = [...document.all].map(e => + window.getComputedStyle(e).zIndex || 0);
 return arr.length ? Math.max(...arr) + 1 : 0
}

Reference resources
javascript Get the largest zIndex value